Method and apparatus for notifying a subframe configuration of multicast broadcast single frequency network

ABSTRACT

The present invention provides a method for notifying Multicast Broadcast Single Frequency Network (MBSFN) subframe configuration, which comprises the following steps: a first node sends its MBSFN subframe configuration, via an X2 interface, to a second node with which the first node is connected; the first node receives the MBSFN subframe configuration of the second node as a feedback. According to the invention, a serving cell can obtain the MBSFN subframe configurations of the neighboring cells and/or RNs, so that rational utilization of resources is achieved according to the configurations. Therefore, interference between cells is reduced, and system capacity and efficiency are improved.

RELATED APPLICATIONS

The present application is a National Phase of International ApplicationNumber PCT/CN2010/071840, filed Apr. 16, 2010 and claims priority from,Chinese Application Number 200910082696.6, filed Apr. 24, 2009.

FIELD OF THE INVENTION

The invention relates to a communication technology, in particular to amethod and apparatus for notifying a subframe configuration of MulticastBroadcast Single Frequency Network (MBSFN).

BACKGROUND OF THE INVENTION

In a current Long Term Evolution (LTE) system, frame structures of bothFrequency Division Duplex (FDD) and Time Division Duplex (TDD) have thelength of 1 ms, respectively. FIG. 1 shows the frame structure ofLTE-TDD according to the prior art, wherein a half-frame of respectiveTDD radio frame consists of five subframes, respective of which has thelength of 1 ms and contains two slots of 0.5 ms.

With increasing lack of frequency resources, more and more attentionsare paid to Single Frequency Network (SFN) both in the field of digitaltelevision terrestrial broadcasting or in mobile communicationtechnology. Basing on the SFN, several transmitters of a certaingeographic region transmit identical signals on the same frequency bandsimultaneously to realize a reliable coverage of this region. In the SFNrealized in Multimedia Broadcast and Multicast Service (MBMS), severalbase stations transmit identical signals with the same frequencysimultaneously. The distribution of Multicast Broadcast Single FrequencyNetwork (MBSFN) is classified as: Radio Frame and Sub Frame.

The disadvantages of the prior art are: when the radii of neighboringcells change according to requirements of coverage, the MBSFN subframeconfigurations of the neighboring cells may be different from that ofthe eNB, as an eNB fails to obtain the subframe configurations of theMBSFN in the neighboring cells. Therefore, interference between theneighboring cells and the base station occurs, and system capacity andservice quality are influenced. In addition, the eNB fails to obtain thesubframe configurations of the MBSFN in the neighboring cells and notifya User Equipment (UE) of it, thereby measurements for the cell will beinfluenced.

SUMMARY OF THE INVENTION

Owing to the above, the object of the present invention is to solve atleast one of the above technical defects, in particular to solve thedefect of the prior art that the eNB fails to obtain the subframeconfigurations of the MBSFN in the neighboring cells.

In order to achieve this object, one aspect of the present inventionproposes a method for notifying MBSFN subframe configurations, whichcomprises the following steps: a first node sends its MBSFN subframeconfiguration, via an X2 interface, to a second node with which thefirst node is connected; the first node receives MBSFN subframeconfigurations of the second nodes fed back by them.

The present invention also proposes an apparatus for notifying MBSFNsubframe configurations, which comprises a sending module and areceiving module, wherein the sending module is configured for sendingthe MBSFN subframe configuration of an eNB, via an X2 interface, torespective neighboring cells and/or RNs, and the receiving module isconfigured for receiving the MBSFN subframe configurations of therespective neighboring cells as a feedback.

The present invention also proposes an apparatus for notifying MBSFNsubframe configurations, which comprises a receiving module and afeedback module, wherein the receiving module is configured forreceiving the MBSFN subframe configurations from a plurality of firstnodes; the feedback module is configured for feeding the MBSFN subframeconfiguration of the second node back to respective first nodes.

According to the invention, a serving cell can obtain the MBSFN subframeconfigurations of the neighboring cells and/or RNs, so that rationalutilization of resources is achieved according to the configurations.Therefore, interference between cells is reduced, and system capacityand efficiency are improved.

Other aspects and advantages of the present invention will beillustrated in the following description and part of them will becomeapparent through the following description or be understood through theembodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or additional aspects and advantages of the presentinvention will become apparent and easily understood from the followingdescription of the embodiments in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a diagram showing a frame structure of LTE-TDD in the priorart.

FIG. 2 is a flowchart showing a method for notifying MBSFN subframeconfigurations according to an embodiment of the present invention.

FIG. 3 is a detailed flowchart showing the method for notifying MBSFNsubframe configurations according to the embodiment of the presentinvention.

FIG. 4 is a schematic structural diagram showing an apparatus fornotifying MBSFN subframe configurations according to an embodiment ofthe present invention.

FIG. 5 is a schematic structural diagram showing an apparatus fornotifying MBSFN subframe configurations according to an embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Hereafter, the embodiments of the present invention will be illustratedin detail, and the examples of the embodiments are shown in figures,wherein identical or similar reference numbers designate an identical orsimilar element or elements having identical or similar functionsthroughout. The following embodiments described with reference to thefigures are merely exemplary and are only used to illustrate the presentinvention rather than being construed as limiting the present invention.

The present invention enables eNB (or RN) to obtain the MBSFN subframeconfigurations of neighboring cells and/or RNs (or eNBs) withinteraction between them, and rational utilization of resources isachieved according to the configurations, thereby interference betweencells is reduced, and system capacity and efficiency are improved.

FIG. 2 is a flowchart showing a method for notifying MBSFN subframeconfigurations according to an embodiment of the present invention. Asshown in FIG. 2, the method comprises the following steps:

S202: a first node sends its MBSFN subframe configuration, via an X2interface, to a second node with which the first node is connected;

S204: the first node receives MBSFN subframe configurations of thesecond nodes fed back by respective second nodes;

S206: the first node makes scheduling according to the MBSFN subframeconfigurations of respective second nodes, while the second node mayalso make scheduling according to the MBSFN subframe configuration ofthe first node.

When a cell is set up, the step of the first node sending its MBSFNsubframe configuration to respective second nodes via an X2 interfacecomprises: the first node sends its MBSFN subframe configuration torespective second nodes with X2 setup request messages.

The step of the first node receiving the feedback MBSFN subframeconfigurations of respective second nodes comprises: the first nodereceives the MBSFN subframe configurations of respective second nodesfeedback by X2 setup response messages.

After the first node receives the feedback MBSFN subframe configurationsof respective second nodes, the method also comprises: the first nodecompares the MBSFN subframe configurations of respective second nodeswith the MBSFN subframe configuration of the first node, and sets systeminformation or radio resource control RRC connection reconfigurationinformation according to a comparison result.

After the second node receives the sent MBSFN subframe configuration ofthe first node, the method also comprises: the second nodes compare theMBSFN subframe configuration of the first node with the MBSFN subframeconfigurations of the second nodes, and set system information or radioresource control RRC connection reconfiguration information according toa comparison result.

When the MBSFN subframe configuration of the first node changes, thestep of the first node sending its MBSFN subframe configuration torespective second nodes via the X2 interface comprises: the first nodesends its MBSFN subframe configuration to the respective second nodeswith the X2 configuration update message of the first node. Similarly,when the MBSFN subframe configurations of the second nodes change, thesecond nodes send their MBSFN subframe configurations to the first nodewith the X2 configuration update messages of the second nodes.

The first node may be an eNB or a RN, and the second nodes may beneighboring eNBs or RNs.

FIG. 3 is a flowchart showing the method for notifying MBSFN subframeconfigurations according to an embodiment of the present invention. Inthis embodiment, interaction of the MBSFN subframe configurationsbetween the eNB of the serving cell and the neighboring cells isdescribed as an example. However, it should be explained that thepresent invention is not limited to this embodiment. The interaction ofthe MBSFN subframe configurations between the eNB and RN as well asbetween RN and RN may also be implemented with reference to thisembodiment. This embodiment comprises the following steps:

S302: when a cell is set up, MBSFN subframe configurations are set byO&M (operation and management) or other means.

S304: an eNB of a serving cell sends its MBSFN subframe configuration torespective neighboring cells via an X2 interface.

Particularly, in one embodiment of the present invention, the eNB sendsits MBSFN subframe configuration to respective neighboring cells with X2setup request messages. More particularly, the eNB adds the MBSFNsubframe configuration into serving cell information and sends it torespective neighboring cells with X2 setup request messages. The servingcell information is shown in the following table:

Information type Information description Physical layer ID Physicallayer ID of cells Cell ID Cell ID, Tracking area code Tracking area codePLMN of broadcasting information of all providers' network shared by thecell >PLMN ID providers' network ID Frequency point Central workingfrequency of the cell Uplink transmission Uplink transmission bandwidthof the cell bandwidth Downlink transmission Downlink transmissionbandwidth of the bandwidth cell Subframe distribution TDD downlink anduplink subframe configuration Special subframe Special subframedistribution distribution MBSFN subframe MBSFN subframe distributiondistribution

It should be explained that the eNB may send its subframe configurationto the neighboring cells with other methods, and it is not limited toadding its subframe configuration into the serving cell information,which is only an exemplary embodiment for realizing the presentinvention rather than limiting the present invention.

S306: the eNB receives the MBSFN subframe configurations of therespective neighboring cells as feedback.

In one embodiment of the present invention, the eNB receives the MBSFNsubframe configurations of the respective neighboring cells feedback byX2 setup response messages. Particularly, the MBSFN subframeconfigurations may also be added into the serving cell information forsending.

S308: after receiving the MBSFN subframe configurations of all theneighboring cells, the eNB compares the MBSFN subframe configurations ofrespective neighboring cells with its MBSFN subframe configuration, andsets system information or RRC (radio resource control) connectionreconfiguration information according to the comparison result. Forexample, NeighCellConfig information is correctly configured in abroadcasting message SIB3/SIB5 or RRC connection reconfigurationinformation. If the MBSFN subframe configuration of at least oneneighboring cell is different from that of the eNB, then NeighCellConfiginformation is set as 00; if the MBSFN subframe configurations of allneighboring cells are the same as that of the eNB, then NeighCellConfiginformation is set as 10; if none of all neighboring cells feeds backthe MBSFN subframe configuration, then NeighCellConfig information isset as 01.

In a preferable embodiment of the present invention, the eNB may makescheduling according to the MBSFN subframe configurations of respectiveneighboring cells. For example, after the eNB obtains the MBSFN subframeconfigurations of the neighboring cells, which may be the reconfiguredMBSFN subframe configurations, the resource utilization is definedaccording to the configurations of respective cells. As the MBSFNsubframe of the neighboring cells may cause relative strong interferencewith the current cell, it should try to avoid corresponding to thesubframe of the current cell during the scheduling according to theobtained MBSFN subframe configuration of the neighboring cells. Forexample, supposed that the MBSFN subframe of the neighboring cell is setas 1, 3, 5, the subframe of the eNB should be preferably set as 2, 4,and 6 during the scheduling. When the subframe of the eNB has to bechosen from what the MBSFN subframe of the neighboring cell is set, ahigher coding protection level should be used, e.g., ⅓ coding instead of⅔ coding, or a lower scheduling level should be used, such as QPSKdegraded from 16 jQAM. Moreover, the nearer UE is chosen for scheduling.For example, the eNB may determine which UE is nearer to the eNBaccording to reported RSRP or RSRQ from the UE.

In another embodiment of the present invention, when its MBSFN subframeconfiguration changes, the eNB may send its MBSFN subframe configurationto respective neighboring cells with an eNB X2 configuration updatemessage to notify all neighboring cells of its new configuration.

The above embodiments of the interaction between the eNB and theneighboring cells are described as examples. In other embodiments of thepresent invention, however, the eNB may also communicate with RNs towhich the eNB is connected for the same sending as the aboveembodiments. The MBSFN subframe configuration information is transmittedvia X2 interface as follows:

MBSFN-SubframeConfig ( relay ) ::= SEQUENCE { radioframeAllocationPeriodENUMERATED {n1, n2, n4, n8, n16, n32}, radioframeAllocationOffsetINTEGER (0..7), subframeAllocation CHOICE { oneFrame BIT STRING(SIZE(6)), fourFrames BIT STRING (SIZE(24)) }

FIG. 4 is a schematic structural diagram showing an apparatus fornotifying MBSFN subframe configurations according to an embodiment ofthe present invention. The apparatus 100 for notifying the MBSFNsubframe configuration comprises a sending module 110 and a receivingmodule 120, wherein the sending module 110 is configured for sendingMBSFN subframe configuration of the first node, via an X2 interface, tothe second nodes to which the first node is connected. The receivingmodule 120 is configured for receiving the MBSFN subframe configurationof the respective second nodes fed back by them.

In one embodiment of the present invention, when a cell is set up, thesending module 110 is configured for sending the MBSFN subframeconfiguration of the first node to respective neighboring cells and/orRNs with X2 setup request messages.

In one embodiment of the present invention, the receiving module 120 isconfigured for receiving the MBSFN subframe configurations of respectivesecond nodes feedback by X2 setup response messages.

In one embodiment of the present invention, the apparatus 100 fornotifying the MBSFN subframe configuration also comprises a comparingand setting module 130, which is configured for comparing the MBSFNsubframe configurations of respective second nodes with the MBSFNsubframe configuration of the first node, and setting system informationor RRC connection reconfiguration information according to thecomparison result.

In one embodiment of the present invention, the apparatus 100 fornotifying the MBSFN subframe configuration also comprises a schedulingmodule 140, which is configured for making scheduling according to theMBSFN subframe configurations of respective second nodes.

In one embodiment of the present invention, the sending module 110 isalso is configured for sending the MBSFN subframe configuration of thefirst node to respective second nodes with X2 configuration updatemessages when the MBSFN subframe configuration of the first nodechanges.

The first node may be an eNB or a RN, and the second nodes may beneighboring eNBs or RNs.

FIG. 5 is a schematic structural diagram showing an apparatus fornotifying MBSFN subframe configurations according to an embodiment ofthe present invention. As shown in FIG. 5, the apparatus 500 comprises areceiving module 502 and a feedback module 504. The receiving module 502is configured for receiving the MBSFN subframe configurations from aplurality of first nodes. The feedback module 504 is configured forfeeding the MBSFN subframe configuration of the second node back torespective first nodes.

The apparatus also comprises a comparing and setting module 506, whichis configured for comparing the MBSFN subframe configuration of thesecond node with the MBSFN subframe configurations of the respectivefirst nodes and setting system information or RRC connectionreconfiguration information according to the comparison result.

The apparatus also comprises a scheduling module 508, which isconfigured for making scheduling according to the MBSFN subframeconfigurations of the respective first nodes.

When the MBSFN subframe configuration of the second node changes, thefeedback module feeding the MBSFN subframe configuration of the secondnode back to respective first nodes via X2 interface comprises: thefeedback module feeds the MBSFN subframe configuration of the secondnode back to the first node with a X2 configuration update message ofthe second node.

The first nodes may be eNBs or RNs, and the second node may be aneighboring eNB or RN.

According to the invention, a first node (such as a serving cell) canobtain the MBSFN subframe configuration of a second node (such as aneighboring cell and/or RN), while the second node can also obtain theMBSFN subframe configuration of the first node, so that rationalutilization of resources is achieved according to the configurations.Therefore interference between cells is reduced, and system capacity andefficiency are improved.

Whereas the embodiments of the present invention have been shown anddescribed, for a person skilled in the art, it should be understood thatthese embodiments can be subjected to various changes, modifications,replacements and deformations without departing from the principle andspirits of the present invention, and the scope of the present inventionis limited by the appended claims and their equivalents.

What is claimed:
 1. A method for notifying Multicast Broadcast SingleFrequency Network (MBSFN) subframe configuration, comprising: a firstnode sending its MBSFN subframe configuration, via an X2 interface, to aplurality of second nodes to which the first node is connected, whereinthe MBSFN subframe configuration of the first node includes X2configuration update messages of the first node if the MBSFN subframeconfiguration of the first node changes; if the first node receives theMBSFN subframe configurations of the respective second nodes asfeedback; the first node compares the MBSFN subframe configurations ofthe respective second nodes with the MBSFN subframe configuration of thefirst node, and sets system information or a radio resource control(RRC) connection reconfiguration information according to the comparisonresult, wherein the system information or the RRC connectionreconfiguration information includes a first bit sequence, and the firstbit sequence is set based on the outcome of the comparison result; andif the first node does not receive the feedback MBSFN subframeconfigurations of the respective second nodes, the first node sets thesystem information or the RRC connection reconfiguration informationaccording to a second bit sequence different than the first bitsequence.
 2. The method for notifying MBSFN subframe configuration ofclaim 1, wherein, when a cell is set up, the first node sending itsMBSFN subframe configuration to the respective second nodes via an X2interface comprises: the first node sending its MBSFN subframeconfiguration to the respective second nodes with one or more X2 setuprequest messages.
 3. The method for notifying MBSFN subframeconfiguration of claim 1, wherein, the first node receiving the MBSFNsubframe configurations of the respective second nodes as feedbackcomprises: the first node receiving the MBSFN subframe configurations ofthe respective second nodes feedback by one or more X2 setup responsemessages.
 4. The method for notifying MBSFN subframe configuration ofclaim 3, further comprising: the first node making scheduling accordingto the MBSFN subframe configurations of the respective second nodes. 5.The method for notifying MBSFN subframe configuration of claim 1,wherein, after the second node receives the sent MBSFN subframeconfiguration of the first node, it further comprises: the second nodecomparing the MBSFN subframe configuration of the first node with theMBSFN subframe configurations of the second node, and setting systeminformation or radio resource control RRC connection reconfigurationinformation according to the comparison result.
 6. The method fornotifying MBSFN subframe configuration of claim 5, further comprising:the second node making scheduling according to the MBSFN subframeconfiguration of the first node.
 7. The method for notifying MBSFNsubframe configuration of claim 1, wherein, when the MBSFN subframeconfiguration of the second node changes, the second node sending itsMBSFN subframe configuration to the first node via the X2 interfacecomprises: the second nodes sending their MBSFN subframe configurationsto the first node with X2 configuration update messages of the secondnodes.
 8. The method for notifying MBSFN subframe configuration of claim1, wherein, the first node is an evolved Node B (eNB) or a relay node(RN), while the second nodes are the neighboring eNBs or RNs of thefirst node.
 9. An apparatus for notifying Multicast Broadcast SingleFrequency Network (MBSFN) subframe configuration, comprising an evolvedNode B (eNB) configured for: sending the MBSFN subframe configuration ofa first node, via an X2 interface, to a plurality of second nodes,wherein the MBSFN subframe configuration of the first node includes X2configuration update messages of the first node if the MBSFN subframeconfiguration of the first node changes; receiving the MBSFN subframeconfigurations of the respective second nodes as feedback; comparing theMBSFN subframe configurations of the respective second nodes with theMBSFN subframe configuration of the first node, and setting systeminformation or a radio resource control (RRC) connection reconfigurationinformation according to the comparison result, wherein the systeminformation or the RRC connection reconfiguration information includes afirst bit sequence set based on the outcome of the comparison result, ifthe MBSFN subframe configuration of the second node is fed back to therespective first nodes; and setting the system information or the RRCconnection reconfiguration information according to a second bitsequence different than the first bit sequence, if the MBSFN subframeconfiguration of the respective second nodes is not fed back to therespective first nodes.
 10. The apparatus of claim 9, wherein, when acell is set up, the eNB is further configured for: sending the MBSFNsubframe configuration of the first node to the respective second nodeswith one or more X2 setup request messages; and receiving the MBSFNsubframe configurations of the respective second nodes feedback by oneor more X2 setup response messages.
 11. The apparatus of claim 9,wherein the eNB is further configured for scheduling according to theMBSFN subframe configurations of the respective second nodes.
 12. Theapparatus of claim 9, wherein, the first node is an evolved Node B (eNB)or a relay node (RN), while the second node is the neighboring eNB or RNof the first node.
 13. An apparatus for notifying Multicast BroadcastSingle Frequency Network (MBSFN) subframe configuration, comprising anevolved Node B (eNB) configured for: receiving the MBSFN subframeconfigurations from a plurality of first nodes; feeding the MBSFNsubframe configuration of a second node back to the respective firstnodes, wherein the MBSFN subframe configuration of the second nodeincludes X2 configuration update messages of the second node if theMBSFN subframe configuration of the second node changes; comparing theMBSFN subframe configuration of the second node with the MBSFN subframeconfigurations of the respective first nodes, and setting systeminformation or a radio resource control (RRC) connection reconfigurationinformation according to the comparison result, wherein the systeminformation or the RRC connection reconfiguration information includes afirst bit sequence set based on the outcome of the comparison result, ifthe MBSFN subframe configuration of the second node is fed back to therespective first nodes; and setting the system information or the RRCconnection reconfiguration information according to a second bitsequence different than the first bit sequence, if the MBSFN subframeconfiguration of the respective second nodes is not fed back to therespective first nodes.
 14. The apparatus of claim 13, wherein the eNBis further configured for scheduling according to the MBSFN subframeconfigurations of the respective first nodes.
 15. The apparatus of claim13, wherein, the first nodes are evolved Node Bs (eNBs) or relay nodes(RNs), and the second node is a neighboring eNB or RN.